Plasma preparation of coal to combustion in power boilers

This paper presents plasma technology for solid fuel ignition and combustion promoting more effective and environmentally friendly low-rank coal incineration. To realize this technology at coal-fired power plants plasma-fuel systems (PFS) were developed. PFS are pulverized coal burner equipped with plasmatron. The technology is based on plasma thermo-chemical preparation of coal for burning. It consists of heating of the pulverized coal and air mixture by arc plasma up to temperature of coal volatile release and char carbon partial gasification. In the PFS carbon is oxidized mainly to carbon monoxide. As a result, at the PFS exit a high reactivity mixture is formed with combustible gases and partially burned char particles, together with the products of combustion, while the temperature of the products is around 1000 degrees C. Further mixing with air promotes intensive ignition and complete combustion of the prepared fuel. Combustion of pulverized coal flame was numerically simulated. The results of calculations of the processes of conventional and plasma activated coal combustion in experimental and full-scale furnaces are discussed. Influence of plasma activation of combustion onto thermo-technical characteristics of the flame, decrease of unburned carbon and nitrogen oxide concentrations at the furnace exit was discovered. (C) 2012 Elsevier B.V. All rights reserved.